The present invention relates to a polymeric electrolyte and a nonaqueous electrolyte which can improve a transport rate of charge carrier ions upon using a compound having boron atoms in the structure as an additive, and an electric device using the same.
According to the development of cells having a high voltage and a high capacity, a large number of various polymeric electrolytes and nonaqueous electrolytes have been proposed. However, polymeric electrolytes and nonaqueous electrolytes have an ionic conductivity which is lower than that of aqueous electrolytes by more than one figure. Further, for example, a polymeric electrolyte using polyethylene glycol has defects that it is low in transfer and transport rates of charge carrier ions. Thus, attempts of improvement have been made by using various methods.
Meanwhile, when nonaqueous electrolytes are applied to cells, they are problematic in that charge/discharge efficiency and cycle characteristics are low. Therefore, in order to improve these, a solvent composition of an electrolytic solution and a type of a support salt has been studied, and a system in which an additive is added to a nonaqueous electrolyte has been studied. For example, Japanese Patent Laid-Open No. 3,728/1999 discloses a nonaqueous electrolytic solution secondary cell comprising a positive electrode and a negative electrode containing a material capable of occluding and releasing lithium reversibly, a nonaqueous electrolytic solution containing a lithium salt and a separator, at least one organic boron compound being contained in the cell in a predetermined amount.
However, these prior techniques have posed a problem that an effective concentration region of an additive is narrow and further an effect provided by its addition per weight is small.
In view of the foregoing, the invention has been made, and aims to provide a polymeric electrolyte and a nonaqueous electrolyte which increases a dissociation degree of an electrolytic salt, which can improve a transport rate of charge carrier ions and in which an effective concentration region of an additive is wide and an effect provided by its addition per weight is great, and an electric device using the same.
The present inventors have assiduously conducted investigations to solve the problems. They have consequently conceived that counter ions of charge carrier ions are trapped and less moved to control a transport rate of charge carrier ions, and have found that the use of a compound containing plural trivalent boron atoms in the structure, a Lewis acid, as an additive, is effective for solving the problems. This finding has led to the completion of the invention.
That is, the polymeric electrolyte of the invention is a polymeric electrolyte made of an electrolytic salt and a polymeric compound forming a complex with the electrolytic salt, the polymeric electrolyte containing one or more compounds having boron atoms in the structure.
Further, the nonaqueous electrolyte of the invention is a nonaqueous electrolyte made of an electrolytic salt and a nonaqueous solvent that dissolves the electrolytic salt, the nonaqueous electrolyte containing one or more compounds having boron atoms in the structure.
The compound having boron atoms in the structure is preferably selected from the group consisting of compounds represented by the following general formulas (1) to (4). 
R11, R12, R13, R14, R15 and R16 formula (1), R21, R22, R23, R24, R25, R26, R27 and R28 in formula (2), R31, R32, R33, R34, R35, R36, R37, R38, R39 and R310 in formula (3), and R41, R42, R43, R44, R45, R46, R47, R48, R49, R410, R411 and R412 in formula (4), which may be the same or different, each represent a hydrogen atom, a halogen atom or a monovalent group, or are bound to each other to form a ring.
Ra in formula (1) represents a group having a site capable of being bound to at least 3 boron atoms which are the same or different, Rb in formula (2) represents a group having a site capable of being bound to at least 4 boron atoms which are the same or different, Rc in formula (3) represents a group having a site capable of being bound to at least 5 boron atoms which are the same or different, and Rd in formula (4) represents a group having a site capable of being bound to at least 6 boron atoms which are the same or different.
The polymeric compound used in the polymeric electrolyte of the invention includes, for example, a polyalkylene, a polyether, a polyester, a polyamine, a polyimide, a polyurethane, a polysulfide, a polyphosphazene, a polysiloxane, derivatives thereof, copolymers thereof and crosslinked products thereof. Alternatively, it includes a polyalkylene oxide, polyvinylidene fluoride, polyhexafluoropropylene, polyacrylonitrile, polymethyl methacrylate, derivatives thereof, copolymers thereof and crosslinked products thereof.
As the electrolytic salt, a lithium salt is preferably used. Further, as the nonaqueous solvent, an aprotic solvent is preferably used.
The electric device of the invention is manufactured using any of the polymeric electrolytes and the nonaqueous electrolytes. For example, when the electric device is a cell, it is obtained by linking a positive electrode and a negative electrode through any of the polymeric electrolytes or through any of the nonaqueous electrolytes and a separator.
Preferable embodiments of the invention are described below. However, the invention is not limited thereto.
With respect to the compound having boron atoms in the structure, which is added to a polymeric electrolyte or a nonaqueous electrolyte of the invention, the compounds represented by general formulas (1) to (4) are preferably used as described earlier. 
R11, R12, R13, R14, R15 and R16 in formula (1), R21, R22, R23, R24, R25, R26, R27 and R28 in formula (2), R31, R32, R33, R34, R35, R36, R37, R38, R39 and R310 in formula (3), and R41, R42, R43, R44, R45, R46, R47, R48, R49, R410, R411 and R412 in formula (4), which may be the same or different, each represent a hydrogen atom, a halogen atom or a monovalent group.
Examples of the monovalent group include an alkyl group, an alkoxy group, an aryl group, an alkenyl group, an alkinyl group, an aralkyl group, a cycloalkyl group, a cyano group, a hydroxyl group, a formyl group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, a sulfonyloxy group, an amino group, an alkylamino group, an arylamino group, a carboxyamino group, an oxysulfonylamino group, a sulfonamido group, an oxycarbonylamino group, a ureido group, an acyl group, an oxycarbonyl group, a carbamoyl group, a sulfonyl group, a sulfinyl group, an oxysulfonyl group, a sulfamoyl group, a carboxylic group, a sulfonic group, a phosphonic group, a heterocyclic group, xe2x80x94B(R1)(R2), xe2x80x94OB(R1)(R2) and xe2x80x94OSi(R1)(R2)(R3). Of these, an alkyl group, an aryl group and fluorine-substituted derivatives thereof are preferable. R1, R2 and R3herein each represent a hydrogen atom, a halogen atom or a monovalent group. Examples of the monovalent group include an alkyl group, an alkoxy group, an aryl group, an alkenyl group, an alkinyl group, an aralkyl group, a cycloalkyl group, a cyano group, a hydroxyl group, a formyl group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, a sulfonyloxy group, an amino group, an alkylamino group, an arylamino group, a carboxyamino group, an oxysulfonylamino group, a sulfonamide group, an oxycarbonylamino group, a ureido group, an acyl group, an oxycarbonyl group, a carbamoyl group, a sulfonyl group, a sulfinyl group, an oxysulfonyl group, a sulfamoyl group, a carboxylic group, a sulfonic group, a phosphonic group, a heterocyclic group and derivatives thereof.
Further, R11, R12, R13, R14, R15 and R16 in formula (1), R21, R22, R23, R24, R25, R26, R27 and R28 in formula (2), R31, R32, R33, R34, R35, R36, R37, R38 and R310 in formula (3), and R41, R42, R43, R44, R45, R46, R47, R48, R49, R410, R411 and R412 in formula (4) may be bound to each other to form a ring, and this ring may have a substituent. Moreover, each group may be substituted with a group which can be substituted.
Examples of the group having a site capable of being bound to at least 3 boron atoms which are the same or different, as represented by Ra, in formula (1) include residues such as glycerin, trimethylolethane, trihydroxybenzene, dihydroxybenzoic acid, diaminobenzoic acid, tribromobenzene and the like.
Examples of the group having a site capable of being bound to at least 4 boron atoms which are the same or different, as represented by Rb, in formula (2) include residues such as diglycerin, pentaerythritol, tetrabromobenzene and the like.
Examples of the group having a site capable of being bound to at least 5 boron atoms which are the same or different, as represented by Rc, in formula (3) include residues such as glucose, morin and the like.
Examples of the group having a site capable of being bound to at least 6 boron atoms which are the same or different, as represented by Rd, in formula (4) include residues such as galactaric acid, myricetin and the like.
The compounds represented by the foregoing general formulas (1) to (4) may be used either singly or in combination.